1. Field of the Invention
The present invention relates to power management of an integrated circuit (IC) and, more specifically, to dynamic and/or adaptive adjustment of a power-supply voltage for a digital processing component of the IC.
2. Description of the Related Art
An important criterion in evaluating the performance of an electronic device is its power consumption. The demand for data-intensive features in portable electronic devices has significantly increased the strain on the battery. Device manufacturers are challenged with offering new features, such as color displays, high-quality sound, web browsing, video streaming, gaming, etc., without sacrificing battery life and the device's form factor. Battery and power-conversion technologies have substantially reached a plateau that offers only modest advances in the near future. As a result, electronic device manufacturers seek to power new features through “smart” power management that leverages the already-existing power capacity so that both the additional power demands and consumer expectations can be met.
Two major components of smart power management are adaptive power control and dynamic power control. Adaptive power control relies on choosing the clock speed and/or supply voltage based upon the process corner that the electronic device was subject to when manufactured and the silicon temperature at which the device is operating. For example, relatively fast devices, which are characterized by relatively high silicon speeds, can be configured to run at lower supply voltages to achieve a desired operating speed, thereby reducing excess power drain on the battery. Dynamic power control relies on changing the clock frequency and/or supply voltage on the fly to respective relatively low (preferably minimum) value(s) that still enable the device to complete a pending task on time. The resulting power savings originate in the CV2 f nature of digital-circuit power consumption, where C is the effective capacitance of the digital circuit, V is the supply voltage, and f is the clock speed. While adaptive power control settings vary from device to device and are normally set one time per device, dynamic power control settings for each particular device vary over time relative to the adaptive power control setting of that device. Further power savings can be realized if the operating temperature of the device is factored into the determination of the supply voltage.
Representative examples of dynamic power control are disclosed, e.g., in U.S. Pat. No. 7,137,013, which is incorporated herein in its entirety. Representative examples of adaptive power control are disclosed, e.g., in U.S. Pat. Nos. 7,106,040 and 7,117,378, both of which are incorporated herein in their entirety. A representative example of combined dynamic and adaptive power control is embodied by the PowerWise™ technology described, e.g., in a white paper available from ARM Limited of the United Kingdom and National Semiconductor Corporation of Santa Clara, Calif. Due to the importance of smart power management, the development of suitable hardware architectures and hardware optimization represent an ongoing concern for electronic device manufacturers.